// Copyright (C) 2025 Kumo inc.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//

#ifndef ROTHAR_PEGTL_CONTRIB_INTERNAL_PEEK_UTF32_HPP
#define ROTHAR_PEGTL_CONTRIB_INTERNAL_PEEK_UTF32_HPP

#include <cstddef>

#include "../../config.hpp"
#include "../../internal/input_pair.hpp"

#include "read_uint.hpp"

namespace rothar::internal
{
   template< typename R >
   struct peek_utf32_impl
   {
      using data_t = char32_t;
      using pair_t = input_pair< char32_t >;

      static_assert( sizeof( char32_t ) == 4 );

      template< typename ParseInput >
      [[nodiscard]] static pair_t peek( ParseInput& in ) noexcept( noexcept( in.size( 4 ) ) )
      {
         if( in.size( 4 ) < 4 ) {
            return { 0, 0 };
         }
         const char32_t t = R::read( in.current() );
         if( ( t <= 0x10ffff ) && !( t >= 0xd800 && t <= 0xdfff ) ) {
            return { t, 4 };
         }
         return { 0, 0 };
      }
   };

   using peek_utf32_be = peek_utf32_impl< read_uint32_be >;
   using peek_utf32_le = peek_utf32_impl< read_uint32_le >;

}  // namespace rothar::internal

#endif
